Causes of overheating are incorrect fluid level. Lack of torque converter operation. Cooler restriction. Valves in the valve body binding and not allowing correct operation of the clutches and torque converter. If the forward clutches were fried then you had a pressure loss in the system which is either caused by a bad seal or lack of EPC pressure or stuck valves in the valve body. The converter turned blue do to the extensive heat. A converter will turn blue when the transmission usually gets over 300 degrees F. There should have been enough internal damage to replace the transmission with a new one since it is under 12k miles. When a trans overheats you have to spend a lot of extra time in making sure everything is perfect. There is usually a lot of damage to the internal parts the coolers and the case. 2k lbs isnot excessive for this truck. You most likely have had a problem since new and it has taken this long for the trans to mass fail. So in summary it was not overhauled right and if it were at my dealership I would have found more than enough damage to replace the unit.
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